516 BY-PRODUCTS IN SULPHURIC ACID MANUFACTURE

sodium sulphate to absorb water of crystallisation. Thus
channels are formed, with a resultant retardation of the process
of leaching. The lumps have to be removed, and considerable
manual labour expended.

Ram6n and Beskovv l invented a method of overcoming this

(
-e

/-

a

J

FIG. 76.

difficulty, b^ spraying water on the hot ore before taking- it to
the leaching vats. Rame'n afterwards introduced an apparatus
called a " Pre-leacher," 2 illustrated 07 Figs. 76 and 77.

The hot roasted ore leaving the chloridising furnace, instead

Fio. 77.

of being taken direct to the leaching-tanks, is carried to the
hopper feeding the pre-leacher. The hopper a, placed eccen-
trically, commands a revolving table b, and can be regulated
in heigit in order to increase or decrease the amount and
depth spread evenly over the surface of the table.

1 SwdislP.35S72. ^ a. P. 15254 of 1914.

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